Im pretty sure its like hardware mac addresses and there is a lot of variety but not endless. Im like 99% sure a key from a lock can open a bunch of other locks sold but its really unlikely to open a lock sold at the same store. Anyway as for the how our modern mass production machinery has electronics and can be programed to things a bit differently based an a database or some math or such.
this post was submitted on 09 Feb 2026
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Actually, a lot of locks ARE the same. I lived in a brand-new complex years back, and everyone had the same lock and key. It didn't take long for some kids to start breaking into other people's houses, and since it was all under HOA owners couldn't just buy mismatched locks.
Then when I bought a 10 yr old home later, I was sitting at the house when some maintenance crew unlocked my door and walked right in. They tried to tell me I was squatting and it wasn't until they realized they were to do work on my neighbors house. Went and checked with other neighbors and found out a handful of us all had the same keys of about 4 varieties. Ironically, there were even two families that knew this before then and they told us how they bought new locks - and found out that those too were the same key.
So basically, if you buy a new lock, you should have it checked by a locksmith and rekeyed if needed.
and since it was all under HOA owners couldn’t just buy mismatched locks.
as an european, i always roll my eyes at the concept of hoa, but this is definitely wildest i have seen in this context 😂
Yeah, but they were somewhat reasonable about it. You could get new locks to prevent break-ins, but it took them a very long time to figure out what they were going to do. It was all brand new and the locks technically worked, so I guess they had to have meetings to figure out if they needed to sue or to buy new locks, change the design....or whatever the HOA does. They ended up telling everyone to keep their old locks and I think they just rekeyed them? I left during all that mess (not for that reason) so idk.
Yeah even for HOA standards this seems crazy though. Like, not being allowed to change your lock? That seems like a massive security risk. Especially given the circumstances. Why does the HOA even care do they need access to everyone’s place?
New locks usually tell you what key set they are on the package... So you can buy multiple of the same lock to rekey an entire house.
While the locks can be rekeyed to thousands of options, the prepackaged options will only be a few sets.
Yeah, and I think when homes are manufactured they just buy sets in bulk. One would think they would rekey them, but I guess not. I mean, even if they were, you should rekey your locks in any new home anyways - but even I fell victim to that because despite knowing this, no one ever does, and it happened twice. You think one would learn.
They won't bother rekeying, but they normally are buying enough that different sets are inevitable even if they don't actively try.
This video explains how standard locks work.
Basically all the parts of the lock are mass produced. Only the pins are unique. And they're aren't actually unique, just the combinations of pins are.
Each tumbler has 4 to 6 sizes in 3 to 6 holes. They set the combination, then cut the key and put the matching tumblers in a standard housing.
Half the security on most locks is that it's hard to get tools in the tiny slots. The actual number of combinations is small, but difficult to scan through.
I don’t know the answer but there’s a guy on YouTube who easily opens all locks, sometimes by just hitting two together or by insert part of a beer can to, well I’m not even sure what to call it. It’s interesting stuff.
LockPickingLawyer, maybe?
There's another one that popped up pretty recently that almost never uses real locksmithing tools, and just makes a shim out of an aluminium can real quick to pop open a lock. They got Streisand Effect'd by some lock company trying to claim his videos are bullshit becsuse he frequently shows how that particular brand of lock sucks ass.
McNally v Proven Locks
Is probably what you're talking about. And apparently Proven Locks is mostly a shit show with one ok product and full of "hurrdurr American patriot" marketing.
It’s possible. Sorry I can’t remember the name.
Mass produced items are not all the same. They are merely similar, and can have whatever variations the bulk manufacturing process requires or allows.
Not every car made on the same assembly line on the same day had the same options, and near every cake baked in a mass bakery will have a distinct internal structure.
You can never step in the same river twice!
Side question: does anyone know if manufacturers rely on entropy to get the required randomness or if they "enforce" patterns by selecting and directing pins?
There are actually "rules" about which pins may go into which positions. For example, you don't want a very short pin (resulting in a "thick part" on the key's blade) in the first position (closest to the bow, the part you are gripping on a key) and then only longer pins the further you move towards the tip. If you had such key, you could remove it from the lock while the plug is turned as only deeper cuts (for longer pins) are encountered by the first pin. And a deeper cut can take a shorter pin without issues. That's why you don't see keys with a "staircase pattern".
Another limitation is MACS (maximum adjacent cut specification), which governs which cut depths may be adjacent. When you insert a key, the pins ride up and down the cuts on the key. If you were to put a super deep cut next to a super shallow cut, the "slope" gets too steep and the key is hard to insert or remove. This means if you know the depth of one cut and the MACS for this model of lock, you can rule out certain cut depths for its direct neighbors. For example, you know that the key you want to forge has a very deep cut, let's say depth 8, on a particular position. Since we know the model of the lock (the professionals recognize a lock just by looking at the keyhole), we know that MACS is 5 and the deepest possible cut is a 9. The direct neighbors of our 8 can be either a 9 or anything from 7 to 3. They cannot be 1 or 2 since that would violate the MACS and repeating the same depth is also very unusual, so we can rule out 8.
Now add manufacturing tolerances into the equation and the potential key space is getting even smaller.
Edit yes, locks are a great thing to nerd out about.
Since in some cases the wrong key can open a lock, and there are not even unique locks made over the production history of a product, I'd say no. This is not cryptography in most cases.
Most of the parts of a lock are the same. However, the small internal parts, like pins and springs, are variable and can be changed out, usually by a locksmith. Those are the parts that require a matching key.
locks arent useful majority can be broken with the right lockpick. Also they mass produce them with variations so that they dont work on another you would find it hilarious how easy one lock can have multiple key configurations by changing the math behind the pins and keys. It’s more to prevent someone doing it easy and just opening the door than an actual burglary. This is one of those inventions that prevents opportunistic behaviour
The utility of a lock is that it's a clear permission barrier. If you don't have the key and bypass the lock, it's clear at least to you that you aren't using a key. Which can be the difference between ordinary trespass and burglary.
2 fronts I'd say.
- Yeah it makes it clear someone breaking in, was doing the effort to conciously get into something that he wasn't permitted to rather than just, opened the wrong door.
Also would point out, low knowledge low effort crooks, really 9/10 situations there's an easier way to get in than the lock. Your house is far more likely to be broken in by someone smashing a window rather than picking a lock.
You would be surprised at how much opportunity based situations leads to crimes being committed and that opportunities are more important than the crime itself
While I certainly don't want to argue about the wisdom of preventive measures towards petty crime or dangerous outcomes, i think it's worth knowing that even trivially surpassed barriers can alter what recompense or punishment can be provided from a court of law.
For example: There was a big copyright infringement case against an AI company recently, which ended in a settlement of a few thousand dollars per registered work so infringed. Authors whose work wasn't registered were not eligible for the same amount, because the law limits how much they can recover if a work's copyright wasn't registered.
Right tools and skills, which is an important part. Just buying the appropriate pick won't magically make you able to open a disc detainer lock, but sure, wafer pins locks can literally be opened by randomly sticking a paperclip in it and using a tensioner.